1. Field of the Invention
The present invention relates to an art of an exhaust gas purification device comprising a particulate filter configured to collect particulate matter in exhaust gas and disposed in an exhaust system of an internal combustion engine such as a diesel engine.
2. Background Art
Conventionally, a particulate filter (hereinafter, referred to as DPF) is disposed in an exhaust system of an internal combustion engine so as to collect and remove particulate matter (hereinafter, referred to as PM) in exhaust gas. With respect to judging PM accumulation amount of the DPF, there is a well-known method of measuring pressure difference between the front and rear sides of the DPF (for example, see the Patent Literature 1) and a method calculating from an already-known PM discharge amount map of the engine and an engine drive record (for example, see the Patent Literature 2). Following the measured results, “DPF renewal” removing accumulated PM is performed.    Patent Literature 1: the Japanese Patent Laid Open Gazette Hei. 7-189654    Patent Literature 2: the Japanese Patent Laid Open Gazette 2002-97930